External motivation by application of force ("the stick").
External motivation by application of reward ("the carrot").
The most powerful motivation is internal, generally this is curiosity or mission-driven behavior for which the subject already has a mental or cultural configuration. To a certain extent, at the individual level if you need external motivation you have 'already lost' in that you will rarely be able to compete with internally motivated people in specialist endeavors.
Therefore, the best method may be to help rediscover curiosity and interest through play.
This problem as described sounds to me a lot like a subjective lack of energy toward the tools and methods one might use to understand themselves or the world around them. I hope that's similar to what you're getting at with the term "loss of perspective".
A quick way to regain energy-footing is to realign with the problems in one's own life. Start from the subjective. Exposing oneself to the rush of fear as one describes what they're currently up against in life. The product ought to be a list.
Then: What tools does one need to take on those problems? What technologies, systems, algorithms, or research may help? Can the tools help define the problem, measure it, or publish about it?
At this point the product ought to look like a list of optional actions, some of which will naturally seem more interesting than others, so some ranking is done.
From here there is an opportunity to tap into the potential energy and dive into something. However in the early stages the risk is in lack of diversification. It will be important for the individual to return to the listing activities later and provide themselves with new energy-building directions and opportunities. Otherwise the same problem can result again without an important meta-lesson learned.
Just an idea for starters, in case it helps. Good luck and way to go.
not the OP but want to thank you for the advice. i’ve been dragging my feet unable to make/stick to a list of my wants/desires/5-year ideations, I think I’ll try make a list with your framing of problem solving instead.
Hmmm maybe there's not a problem for you to solve at all. There might be personal reasons on why he lost it, and maybe listening on why and what other things he focus now on might be a more insightful and engaging conversation.